A high-speed access system provides an efficient way for a relatively large number of small-scale users to share a high-speed network. It concentrates several service traffic streams to a single point of entry to a high-speed backbone so as to share the broadband service economically. A PON, or passive optical network, is one such system. PON's have gained in popularity because of their capability to supply a high bandwidth at low cost, due to the fact that the splits between lines are of a purely optical and passive nature. PON's have the potential to supply a full range of all currently known and new services being offered and considered for residential and business customers, over a single line. The most common services today are voice and data, where data is transported using IP or ATM protocols.
The use of a PON requires an efficient multiplexing function to manage the mixed upstream service traffic from the multiple users, or NT's, at the connection point to the network, or the LT. Such a protocol is necessary to prevent collisions between the many information transport streams competing for access to the backbone networks through the single LT.
Related art provides for a method of service transport over a PON, using ATM protocols for transfer of all service types. This is called APON. U.S. Pat. No. 5,978,374 and the International Telecommunications Union standard G.983 relate to APON protocols.
This art is a rather cumbersome way to provide service transport over a PON, as all information being transported must be wrapped in ATM cells at one end, and unwrapped at the other. This wrapping and unwrapping requires a significant amount of work, as well as adding significant overhead because of the addition of ATM headers, which is a drain on bandwidth resources. Furthermore, because of the nature of certain synchronous services, such as voice calls, much of this ATM conversion must be done in real-time, requiring the installation of DSP's at all of the network terminations. Such extensive deployment of DSP's raises costs for service providers. A further disadvantage of the prior art is that the need to convert everything to ATM cells increases the potential for jitter.
Alternatively, according to the prior art many businesses rely on separate suppliers for each of their service needs, most notably voice and data, in order to provide native transport of both. This leads to a situation in which such enterprises are dependent on two or more separate technologies provided by two or more separate suppliers, lowering efficiency and raising costs to the business.
It would be desirable to supply all existing and future services over a single line, using native service transport.